Laser communication through the atmosphere is impaired by turbulences in the atmosphere. This effect, known as scintillation, causes fades in the received power and outages in the laser communication for several milliseconds. Due to the high data rate in the order of 1 Gbit/s and beyond, bit error bursts of 1 Mbit and more can be observed. To compensate for this effect, DLR developed a packet level coding scheme, whose code words are longer than such error bursts and thus able to correct the long error bursts in the best possible way without the need of an interleaver. The objective of the project COLT is to design, implement and demonstrate a FPGA based packet level coder and decoder for data rates of about 1 Gbit/s.
The project focuses on laser links between two terrestrial terminals with distances between 500 m and 15 km. The following figure shows an example of the fading of the received power for a laser communication through the atmosphere.
The codeword error rate (CER) vs. codeword length for a 12 km link and code rate R=0.6 is illustrated in the following figure:
Project partner is the Vialight Communications GmbH.
Laufzeit: bis ca. Juni 2017